New atomic parity nonconservation (PNC) experiments will be carried out using Thallium and the rare earth elements erbium, samarium, gadolinium, and perhaps dysprosium. Very large improvements in signal are possible over those obtained in previous experiments, by means of the proposed techniques: hypersonic beams, Stark interference, pulsed laser spectroscopy, and ionization detection. It appears feasible to measure quite accurately nuclear spin dependent PNC effects, and the possibility exists for a good measurement of Weinberg's angle from a comparison of PNC asymmetries. Such a comparison may also be possible in different isotopes of the rare earths. The results of such comparative measurements would be nearly independent of uncertainties in Stark.induced electric.dipole matrix elements and in atomic theory.
